toronto reuters canadian buyout firm onex corp is leading the bidding for swiss juicebox maker sig combibloc group, bloomberg reported on sunday, citing unnamed people familiar with the matter.officials at torontobased onex, canada&39s largest listed private equity firm, did not immediately respond to calls seeking comment.the report said onex may reach an agreement to buy sig for more than 4 billion as early as this week, but that negotiations could still fall apart.reuters reported in june that new zealand&39s richest man, graeme hart, was exploring a sale of sig, the world&39s second largest maker of drink cartons.the billionaire had acquired sig in 2007. the company is based in neuhausen am rheinfall, switzerland, and manufactures aseptic carton packaging that allows juices, milk, soups and sauces to be stored for a long period of time without refrigeration.earlier this month, sources told reuters that buyout groups bc partners, onex and partners group were set to bid for sig, in an auction likely to raise less for hart than initially seemed possible.reporting by jeffrey hodgson editing by muralikumar anantharamansource httpsenmaktoob.news.yahoo.comcanadasonexleadsbiddingpackagingfirmsigbloomberg040527421sector.html